Silica fiber compositions and methods of use

ABSTRACT

Embodiments of the invention include silica fiber compositions useful for treatment of animal wounds and tissue, as well as for other applications in industry. The fiber compositions may be formed via electrospinning of a sol gel produced with a silicon alkoxide reagent, such as tetraethyl ortho silicate, alcohol solvent, and an acid catalyst.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/934,599, filed Mar. 23, 2018, which claims the benefit ofand priority to U.S. Provisional Patent Application No. 62/710,305,filed Feb. 16, 2018, and U.S. Provisional Patent Application No.62/643,946, filed Mar. 16, 2018, the entire disclosure of each of whichis hereby incorporated herein by reference.

TECHNICAL FIELD

In various embodiments, the present invention relates to the fabricationand use of silica fibers.

BACKGROUND

Wound healing involves a well-coordinated series of biological processesthat include both tissue destruction and tissue regeneration. Forexample, during normal wound healing, neutrophils and monocytes arerecruited to the wound during an early inflammatory phase. Theneutrophils phagocytize debris and micro-organisms; monocytes and othercells release enzymes in the surrounding matrix to digest damagedtissue. Fibrin is broken down as part of this process, and thedegradation products attract fibroblasts and epithelial cells to thesite of the wound. Macrophages recruited to the wound (as well as othercells) secrete extracellular enzymes that act on all components of theextracellular matrix and are responsible for removal of devitalizedtissue. Macrophages also secrete a variety of cytokines and growthfactors that can stimulate keratinocytes, fibroblasts and angiogenesis,which promotes the transition to the proliferative phase of healing. Theproliferation phase is characterized by angiogenesis, collagendeposition, granulation tissue formation, wound contraction andepithelialization. Proliferation involves replacement of dermal tissuesas well as contraction of the wound.

While destruction of collagen is important during the early phases ofwound healing, its deposition and remodeling is critical for laterstages. During wound healing, the wound bed fills in from the bottom upwith collagen and must be maintained in an optimal environment(appropriate moisture balance and temperature) before the epithelialcells will begin to proliferate and migrate across the wound's surfaceto close the wound. The collagen structures provide the cells with theneeded biological environment for development, organogenesis, cellgrowth, and wound repair.

Chronic wounds are wounds that have not progressed through this normal,orderly sequence of repair. Further, chronic wounds may eventually passthrough the repair process without restoring sustained anatomical andfunctional tissue. Chronic wounds can result when the body has failed tocorrect for the causes of the wound, and/or where there is not aconducive environment for healing. For example, newly deposited collagencan be enzymatically destroyed by an uncontrolled inflammatory response,making it difficult for dermal cells to populate the wound andproliferate.

The present invention provides compositions and methods for promotingwound healing, including for acute and chronic wounds, and wounds thatresult from physical, biological, or genetic causes that interfere withnormal wound healing physiology.

SUMMARY

The present invention in various aspects and embodiments providesmethods for making silica fiber mats useful for treatment of animalwounds and tissue, as well as for other applications in industry. Themethods comprise preparing a sol with a silicon alkoxide reagent, suchas tetraethyl ortho silicate (TEOS), alcohol solvent, and an acidcatalyst, and transitioning the sol for at least 2 days and less than 7days under conditions where humidity and temperature are controlled. Thesol-gel is electrospun to create a silica fiber mat with superiortexture and properties.

In some embodiments, the composition is a lightweight structure composedof silica fiber (e.g., silicon dioxide nanofiber). By ripening (or“transitioning”) the sol under controlled environmental conditions,and/or monitoring the properties of the sol during theripening/transitioning process, the relatively short window tosuccessfully electrospin the sol-gel can be identified to prepare asuperior composition for wound care and other applications.

In various aspects, the present invention provides compositions andmethods for improving integrity of injured tissue in a subject,including for accelerating or improving healing of acute or chronicwounds. The compositions comprise a silica fiber matrix, which isapplied to injured tissue to support tissue regeneration and healing. Insome embodiments, the silica fiber matrix is a non-biodegradablescaffold that is not removed from the wound (unlike a conventional wounddressing), but becomes integrated with the regenerated tissue.

In accordance with embodiments of the invention, the silica fibercomposition, when applied to wounded tissue, acts as a non-biodegradablescaffold that supports tissue healing, regeneration, and/or integrity.The composition acts as a collagen biomimetic at the site of tissueinjury, providing an environment conducive for regeneration and growthof, for example, dermal cells.

In various embodiments, the controlled environment for transitioning thesol may involve controlled conditions in terms of humidity, temperature,and optionally barometric pressure. For example, the humidity may becontrolled within the range of about 30% to about 90% or from about 40%to about 80%. The temperature may be controlled within the range of fromabout 50° F. to about 90° F. By controlling the environmental conditionsduring transitioning, the gel can be electrospun during the time whenspinning is optimal, which can occur in a very small window of onlyseveral minutes if the ripening process is accelerated by direct heat.When transitioning the sol at a constant humidity in the range of about50% to 70% and a temperature of about 60 to 80° F., the sol willtransition (gelatinize) in a few days, and the window for successfulelectrospinning can be expanded to at least several hours, and in someembodiments several days. The sol may therefore be transitioned in anenclosure which may include an exhaust fan and one or more environmentalmonitors or sensors, such as a temperature reading device and/or ahumidity reading device. Further, gases produced or released by the solduring the transitioning process and/or relative weight of the sol canbe monitored to determine the suitable or optimal time forelectrospinning.

If the sol-gel is prepared to allow for optimal electrospinning, asdescribed herein, it is possible to electrospin fiber mats having athickness of at least about ⅛ inch, or at least about ¼ inch, or atleast about ⅓ inch, or at least about ½ inch, which are easier to handlefor application of fibers to a wound. Indeed, formation of fiber mats ofthicknesses in accordance with embodiments of the present inventionenables the separation, if necessary or desired, of one or more layersof entangled fibers from a single mat for applications such as woundcare.

In some embodiments, the fiber composition is applied to the tissue orwound as a thin layer of fibers, e.g., just enough to cover the wound,followed by repeated application as necessary. In some embodiments, thefiber composition is processed into a fine powder or dust, which isapplied to the tissue. In some embodiments, the powder or dust is mixedwith a topical composition, such as a lotion, ointment, paste, cream,foam, or gel. In these embodiments, the topical composition may compriseone or more pharmaceutical or antimicrobial agents, such as anantibiotic, an antiseptic, an anti-inflammatory agent, orimmunosuppressant.

Application of the composition during the healing process can providefor accelerated healing, of both acute and chronic wounds, and canprevent or reduce tissue scarring. When the topical composition isapplied to the skin that has a blemish like acne, cracks in skin, lossof integrity due to age or environmental insult (sun, wind, or cold,etc.), the scaffolding is left behind in the small wound for cells togrow into. This speeds up the healing process and helps to reducescarring.

In some embodiments, the wound is a first or second degree burn, scrape,or cut, or a minor wound that does not go deeper than the base lamina.In some embodiments, the wound includes damage including or past thebase lamina. In some embodiments, the wound is a third degree burn,diabetic ulcer, chronic pressure sore, or gangrenous wound. In someembodiments, fibers are applied once to four times daily to cover thewound. Fibers are generally reapplied when fibers are no longer visiblein the wound. An additional wound cover can be employed where necessary,as long as air and oxygen are not restricted from the wound.

In some embodiments, the subject has a genetic blistering disease, suchas epidermolysis bullosa (EB). In people born with EB, the two skinlayers lack the protein anchors that hold them together, resulting inextremely fragile skin, where even minor mechanical friction likerubbing or pressure will separate the layers of the skin and formblisters and painful sores. In these embodiments, the composition willbecome integrated with the base lamina, and help anchor the skin. Thus,over time, the skin exhibits improved integrity as sores and blistersare continually treated. Further, the reduction in pain can be importantfor these patients to perform daily activities, such as bathing ortraveling.

In an aspect, embodiments of the invention feature a method forimproving integrity of injured tissue in a subject. The method includes,consists essentially of, or consists of applying a silica fibercomposition to the injured tissue.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The silica fiber composition may be apermanent, non-biodegradable scaffold that supports tissue healing,regeneration, and/or integrity. The composition may act as a collagenreplacement, and/or cell scaffold for wound healing. The composition maybe prepared by electrospinning a sol-gel. The sol-gel may be preparedwith tetraethyl orthosilicate (TEOS). The sol-gel may contain 70% to 90%TEOS by weight, 8% to 25% ethanol by weight, an acid catalyst, and thebalance water. The sol-gel may contain 70% to 90% TEOS by weight, 8% to25% ethanol by weight, 1% to 10% water by weight, and the acid catalyst.The sol-gel may contain 75% to 85% by weight TEOS, 12% to 20% by weightethanol, and about 2% to 5% by weight water.

The sol-gel may contain about 80% by weight TEOS, about 17% by weightethanol, and about 3% by weight water. The acid catalyst may include,consist essentially of, or consist of HCl. The sol-gel may contain lessthan about 0.1% of the acid catalyst by weight. The sol-gel may containfrom 0.02% to 0.08% of the acid catalyst by weight. The sol-gel may beallowed to transition for at least 2 days under conditions wherehumidity is within the range of about 40% to about 80%, and thetemperature is within the range of 50° F. to 90° F. The sol-gel may beallowed to transition for at least 3 days, at least 4 days, at least 5days, at least 6 days, or at least 7 days. The sol-get may be allowed totransition for 2 days to 7 days. The sol-gel may be electrospun when theweight is at from 20% to 40% of the starting weight before ripening(transitioning). The sol-gel may be electrospun when the production ofethylene vapor is 10% to 20% relative to the peak production of ethylenevapors during ripening (transitioning). The sol-gel may be electrospunwhen the production of ethylene vapor therefrom is 10% to 40% relativeto the sol-gel before ripening (transitioning). Fibers of the silicafiber composition may have a variable diameter of from about 50 nm toabout 5 μm. The fibers may have a variable diameter of from about 200 nmto about 1000 nm.

The composition may include, consist essentially of, or consist of SiO₂.The composition may be electrospun with a thickness of from about ⅛ inchto about ¼ inch. The composition may be electrospun with a thickness ofgreater than about ⅛ inch, or greater than about ¼ inch. The fibercomposition may be applied to the tissue as a thin layer (e.g., a layerhaving a thickness less than about 1 inch, less than about ½ inch, lessthan about ¼ inch, or less than about ⅛ inch; the thickness may begreater than about 1/32 inch or greater than about 1/16 inch). The fibercomposition may be processed into a powder or dust or a plurality offibrous fragments, and the powder or dust or fragments may be applied tothe tissue. The powder or dust or fragments may be mixed or suspended ina topical composition. The topical composition may be a lotion,ointment, paste, cream, foam, or gel. The topical composition mayinclude one or more pharmaceutical and/or antimicrobial agents. Thetopical composition may include an antibiotic and/or an antiseptic. Thetopical composition may include an anti-inflammatory agent and/or animmunosuppressant. During and/or after healing of the injured tissue, atleast some of (or even all of) the silica fiber composition may not beremoved from the tissue. The silica fiber composition may be reappliedone or more times to the injured tissue once the silica fibercomposition is no longer visible on the injured tissue. The injuredtissue may not be covered with any other wound dressing. At least aportion of the injured tissue may be covered by an additional wounddressing (e.g., over the composition).

The method may prevent or reduce scarring of the injured tissue. Thesubject may be a mammal. The injured tissue may be skin. The subject maybe a veterinary patient, e.g., a dog, cat, or horse. The subject may bea human patient. The composition may be applied to a skin lesion, ulcer,wound, burn, cut, scrape, or blister. The composition may be applied toa diabetic ulcer. The subject may have a genetic blistering disease. Thesubject may have epidermolysis bullosa. The subject may have a burn,e.g., a second-degree or third-degree burn. The composition may beapplied to a pressure sore or pressure ulcer. The injured tissue may begangrenous and/or may be an amputation wound. The injured tissue may bea cancer lesion. The injured tissue may include, consist essentially of,or consist of a skin burn, cut, or scrape, and the composition may beapplied in one or more layers (e.g., a plurality of layers) in an amountsufficient to cover the injured tissue. The composition may not beremoved from the injured tissue, and the composition may be reappliedonce no longer visible at the injured tissue. The composition may bereapplied after bathing of the subject.

In another aspect, embodiments of the invention feature a silica fibermat composition that includes, consists essentially of, or consists ofsilica fibers prepared by electrospinning a sol-gel prepared withtetraethyl orthosilicate (TEOS), an alcohol solvent, and acid catalyst;the sol-gel having been allowed to transition for at least 2 days underconditions where humidity is within the range of about 40% to about 80%,and the temperature is within the range of 50° F. to 90° F.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The sol-gel may be allowed totransition for at least 3 days, at least 4 days, at least 5 days, atleast 6 days, or at least 7 days. The sol-get may be allowed totransition for 2 days to 7 days. The sol-gel may be electrospun when theweight is at from 20% to 40% of the starting weight before ripening(transitioning). The sol-gel may be electrospun when the production ofethylene vapor is 10% to 20% relative to the peak production of ethylenevapors during ripening (transitioning). The sol-gel may be electrospunwhen the production of ethylene vapor therefrom is 10% to 40% relativeto the sol-gel before ripening (transitioning). Fibers of the silicafiber composition may have a variable diameter of from about 50 nm toabout 5 μm. The fibers may have a variable diameter of from about 200 nmto about 1000 nm. The composition may include, consist essentially of,or consist of SiO₂. The composition may be electrospun with a thicknessof from about ⅛ inch to about ¼ inch. The composition may be electrospunwith a thickness of greater than about ⅛ inch, or greater than about ¼inch.

In yet another aspect, embodiments of the invention feature a fibercomposition that includes, consists essentially of, or consists of (i) asilica fiber powder or dust or plurality of fibrous fragments, and (ii)a topical carrier.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The topical carrier may be a lotion,ointment, paste, cream, foam, or gel. The topical carrier may includeone or more pharmaceutical and/or antimicrobial agents. The topicalcarrier may include an antibiotic and/or antiseptic. The topical carriermay include an anti-inflammatory agent and/or immunosuppressant.

In another aspect, embodiments of the invention feature a method formaking a silica fiber composition. A sol is prepared. The sol includes,consists essentially of, or consists of tetraethyl orthosilicate (TEOS),ethanol, water, and an acid catalyst. The sol may include, consistessentially of, or consist of 70% to 90% TEOS by weight, 8% to 25%ethanol by weight, 1% to 10% water by weight, and the acid catalyst. Thesol is transitioned to a sol-gel for 2 to 7 days. The sol may betransitioned under conditions where humidity is within the range of 40%to 80%, and the temperature is within the range of 50 to 90° F. Thesol-gel is electrospun into a silica fiber mat.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. During preparation and/ortransitioning, the sol may not be exposed to heat over 150° F., over100° F., over 90° F., or over 80° F. The sol may contain 75% to 85% byweight TEOS, 12% to 20% by weight ethanol, and about 2% to 5% by weightwater. The sol may contain about 80% by weight TEOS, about 17% by weightethanol, and about 3% by weight water. The acid catalyst may include,consist essentially of, or consist of HCl. The sol may contain less thanabout 0.1% of the acid catalyst by weight. The sol may contain from0.02% to 0.08% of the acid catalyst by weight. The sol may not containan organic polymer. The composition may include, consist essentially of,or consist of SiO₂. The sol may be allowed to transition for 2 to 4days, e.g., about 3 days. The humidity may be about 50% to about 70%.The temperature may be about 60° F. to about 80° F. The conditions mayinclude an exhaust system (e.g., one or more fans) exhausting gases fromthe sol. The sol-gel may be electrospun when the weight is at from about20% to about 40% of the starting weight of the sol. The sol-gel may beelectrospun when the production of ethylene vapor is about 10% to about20% relative to the peak production of ethylene vapors from the sol. Themat may have a thickness of at least about ⅛ inch, or at least about1/49 inch. The mat may have a thickness of less than about 6 inches,less than about 5 inches, less than about 4 inches, less than about 3inches, less than about 2 inches, or less than about 1 inch.

In yet another aspect, embodiments of the invention feature a method formaking and using a silica fiber composition. A sol is prepared. The solincludes, consists essentially of, or consists of tetraethylorthosilicate (TEOS), ethanol, water, and an acid catalyst. The sol mayinclude, consist essentially of, or consist of 70% to 90% TEOS byweight, 8% to 25% ethanol by weight, 1% to 10% water by weight, and theacid catalyst. The sol is transitioned to a sol-gel for 2 to 7 days. Thesol may be transitioned under conditions where humidity is within therange of 40% to 80%, and the temperature is within the range of 50 to90° F. The sol-gel is electrospun into a silica fiber mat. At least aportion of the silica fiber mat is applied to injured tissue of asubject, the subject being a human or veterinary patient.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. At least some of, or evensubstantially all of, the at least a portion of the silica fiber mat maynot be removed from the issue during and/or after healing of the injuredtissue. At least a portion of the silica fiber mat may be processed intoa powder or dust (e.g., a plurality of powder particles and/or fibrousfragments). The powder or dust may be mixed or suspended with a topicalcomposition. The topical composition may be a lotion, ointment, paste,cream, foam, or gel. The topical composition may include one or morepharmaceutical and/or antimicrobial agents. The topical composition mayinclude an antibiotic, an antiseptic, an anti-inflammatory agent, and/oran immunosuppressant.

In another aspect, embodiments of the invention feature a method formaking and using a silica fiber composition. A sol is prepared. The solincludes, consists essentially of, or consists of tetraethylorthosilicate (TEOS), ethanol, water, and an acid catalyst. The sol mayinclude, consist essentially of, or consist of 70% to 90% TEOS byweight, 8% to 25% ethanol by weight, 1% to 10% water by weight, and theacid catalyst. The sol is transitioned to a sol-gel for 2 to 7 days. Thesol may be transitioned under conditions where humidity is within therange of 40% to 80%, and the temperature is within the range of 50 to90° F. The sol-gel is electrospun into a silica fiber mat. At least aportion of the silica fiber mat may be combined with a liquid orgelatinous composition.

Embodiments of the invention may include one or more of the following inany of a variety of combinations. The liquid or gelatinous compositionmay include, consist essentially of, or consist of a paint, an epoxy, aurethane, and/or an adhesive. The at least a portion of the silica fibermat may be processed into a plurality of fragments or a powder forcombination with the liquid or gelatinous composition, whereby amodified composition is formed. The modified composition may be appliedas a coating to a solid object and/or a fabric. The modified compositionmay be molded into a solid object.

These and other objects, along with advantages and features of thepresent invention herein disclosed, will become more apparent throughreference to the following description, the accompanying drawings, andthe claims. Furthermore, it is to be understood that the features of thevarious embodiments described herein are not mutually exclusive and mayexist in various combinations and permutations. As used herein, theterms “approximately,” “about,” and “substantially” mean ±10%, and insome embodiments, ±5%. The term “consists essentially of” meansexcluding other materials that contribute to function, unless otherwisedefined herein. Nonetheless, such other materials may be present,collectively or individually, in trace amounts.

Other applications of the fiber composition in industry are describedherein. Other aspects and embodiments are described in the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIGS. 1A-1D are scanning electron microscopy (SEM) images of fibers spunin accordance with this disclosure. Images in FIGS. 1A-1D are at,respectively, 50, 100, 200, and 500 micron scale. As shown, the fibersare flexible, smooth, dense, and continuous (not fractured).

FIGS. 2A-2D are SEM images of fibers that were electrospun at anon-optimal time (before the sol-gel was fully ripened). Images in FIGS.2A-2D are at, respectively, 50, 100, 200, and 500 micron scale. Asshown, the fibers appear rigid, with many fractures visible, and withformation of clumps.

FIG. 3 shows an SEM image (20 micron scale is shown) of fibers spun at anon-optimal time. The fibers are rigid, with fractures clearly evident.

FIG. 4 shows a fiber mat spun with a thickness of about ¼ inch inaccordance with the disclosure. The mat has a soft, flexible texture.

FIGS. 5A and 5B compare a silica fiber mat that was electrospun when thesol-gel was transitioned in accordance with this disclosure (FIG. 5A),with a fiber mat that was spun too early, before the sol-gel wasoptimally ripened (FIG. 5B). The material in FIG. 5A has a soft texture,is very flexible, and can be spun at a thickness that is easily handledfor application of fiber layers to a wound. The material in FIG. 5B isbrittle, inflexible, and layers of fiber cannot be easily separated forcovering the surface area of a wound.

FIG. 6 shows application of a thin section of fiber to a burn wound.

FIG. 7A is picture of a burn before application of fibers. FIG. 7B showsthe same wound after 4 days of treatment with the fiber scaffold. FIG.7C shows the same wound after 8 days of treatment with the fiberscaffold. FIG. 7D shows the same wound after 12 days of treatment withthe fiber scaffold.

FIG. 8A is a picture of a dog leg wound with fiber graft. FIG. 8B showsthe wound after about 3 months of treatment.

FIG. 9A is a picture of a wound on a horse leg. The wound aftertreatment with fibers for about 4 days is shown in FIG. 9B. FIG. 9Cshows the wound fully healed.

FIG. 10A is a photograph of a child with Epidermolysis Bullosa (EB),with a graft of the fibers applied to a large open wound on the hand.FIG. 10B shows the same hand after healing.

FIGS. 11A and 11B show application of fibers to a burn wound.

FIGS. 11C and 11D show the wound of FIGS. 11A and 11B eight days afterthe burn occurred. The wound has been replaced by healthy tissue, uponwhich hair is evident. No scarring or scar tissue is visible.

DETAILED DESCRIPTION

The present invention in various aspects and embodiments providesmethods for making silica fiber mats useful for treatment of animalwounds and tissue, as well as other applications in industry. Themethods comprise preparing a sol with a silicon alkoxide reagent, suchas tetraethyl ortho silicate (TEOS), alcohol solvent, and an acidcatalyst, and transitioning the sol for at least 2 days and less than 7days under conditions where humidity and temperature are controlled. Thesol-gel is electrospun to create a silica fiber mat with superiortexture and properties.

The present invention provides compositions and methods for improvingintegrity of injured tissue in a subject, including for accelerating orimproving healing of acute or chronic wounds. The compositions comprisea silica fiber matrix, which is applied to injured or inflamed tissue tosupport tissue regeneration, healing, and/or pain reduction.

In some embodiments, the composition is a lightweight structure composedof silica fiber (e.g., silicon dioxide nanofiber). The composition isformed from a gelatinous material that is electrospun to form a fibermat (e.g., a non-woven mat). For example, the composition may beprepared by electrospinning a sol-gel, which can be prepared with asilicon alkoxide reagent, such as tetraethyl ortho silicate (TEOS),alcohol solvent, and an acid catalyst.

Known processes do not yield a silica fiber composition with sufficientflexibility for many applications, including for wound care or healthcare applications. Instead, these structures are comparatively brittle,rigid, and compact; mats will easily fracture or break; fiber layers aredifficult to separate; and generally lack the physical characteristicsto mimic collagen deposition in a wound. In various embodiments, toachieve a superior material for tissue repair, it is important toelectrospin the sol-gel once it is appropriately ripened (or“transitioned”), to achieve a composition with the desired physicalcharacteristics. By transitioning the sol under controlled environmentalconditions, and/or monitoring the preparation of the sol-gel during theripening process, the relatively short window to successfullyelectrospin the sol-gel can be identified. In accordance withembodiments of the invention, the composition is non-rigid and has asoft texture similar to that of cotton.

In accordance with embodiments of the invention, the silica fibercomposition, when applied to wounded tissue, acts as a non-biodegradablescaffold that supports tissue healing, regeneration, and/or integrity.The composition acts as a collagen biomimetic at the site of tissueinjury, providing an environment conducive for regeneration and growthof dermal cells. Without wishing to be bound by theory, the compositionand methods described herein avoid the problem of temperaturedysregulation as well as excess pain and inflammation at the wound site,allowing for the wound environment to normalize. Further, uncontrolledtissue degradation processes can destroy newly deposited collagen, whichis needed to support tissue regeneration. The composition of theinvention provides a non-biodegradable cell scaffold that is notdestroyed by proteases released at the wound site, but provides anoptimal environment for population and growth of dermal cells. Thefibers will not be removed from the wound, but will become an integralpart of the new tissue.

The fibers may have a variable diameter, such as in the range of fromabout 50 nm to 5 μm. In some embodiments, the fibers are predominatelyin the range of about 100 nm to about 2 μm, or predominately in therange of about 200 to about 800 nm. The variable size of the fibers canbe a better mimic for natural collagen, compared to, for example,scaffolding intended to have a more uniform structure. The differentcell types involved in tissue healing or regeneration require differentsize diameters of collagen. Without intending to be bound by theory,cells that migrate into the fibers have the ability to directpositioning of the fibers, as needed to support growth, adherence, orproliferation of the particular cell. Further, tissue requires a lot ofsurface area, which is provided by the fiber material. This is incontrast to many 3D printing and other synthetic scaffoldingalternatives that lack substantial surface area. Further still,biodegradable scaffoldings, which have been conventionally preferred,typically degrade too quickly, before the tissue has the ability to growand become self-sustainable.

For example, macrophages secrete a variety of cytokines and growthfactors such as fibroblast growth factor (FGF), epidermal growth factor(EGF) and transforming growth factor beta that can stimulatekeratinocytes, fibroblasts, and other cells required for angiogenesis,collagen deposition, granulation tissue formation, wound contraction andepithelialization. Fibroblasts secrete the collagen framework thatallows for dermal regeneration. However, macrophages as well asepithelial cells and fibroblasts also secrete extracellular enzymes(e.g., matrix metalloproteinases, MMPs) at the site of the wound todegrade necrotic tissue and apoptotic cells. MMPs act on all componentsof the extracellular matrix and are responsible for removal ofdevitalized tissue, repair of lost or damaged tissue, and remodeling.MMPs are balanced by tissue inhibitors of metalloproteinases (TIMPs),which are released locally by cells to deactivate the MMPs. Uncontrolledactivity of MMPs may result in degradation of newly formed tissue(including collagen) or destruction of growth factors, which willinterfere with wound healing. By providing the non-biodegradablescaffold, uncontrolled activity of MMPs will not interfere withpopulation and growth of dermal cells.

In some embodiments, the sol-gel for preparing the silica fibercomposition is prepared by a method that includes preparing a firstmixture containing an alcohol solvent, a silicon alkoxide reagent suchas tetraethyl ortho silicate (TEOS); preparing a second mixturecontaining an alcohol solvent, water, and an acid catalyst; fullytitrating the second mixture into the first mixture; and processing(ripening) the combined mixture under controlled environmentalconditions to form a gel for electrospinning.

In some embodiments, the silicon alkoxide reagent is TEOS. Alternativesilicon alkoxide reagents include those with the formula Si(OR)₄, whereR is from 1 to 6, and preferably 1, 2, or 3.

In some embodiments, the alcohol solvent is an anhydrous denaturedethanol, or in some embodiments, methanol, propanol, butanol or anyother suitable alcohol solvent. The first mixture can be agitated, forexample, using a magnetic stirrer or similar agitation means. The secondmixture contains an alcohol solvent, water, and an acid catalyst. Thealcohol solvent may be an anhydrous denatured alcohol, or may bemethanol, propanol, butanol or any other suitably provided alcoholsolvent. Water may be distilled water or deionized water. Enough acidcatalyst is added to the mixture to aid in the reaction. This acidcatalyst may be hydrochloric acid, or may be sulfuric acid or othersuitable acid catalyst. The second mixture may be agitated, for example,with a magnetic stirrer or other agitation means. In some embodiments,the first mixture (or sol) and the second mixture (or sol) are createdwithout the use of direct heat.

In some embodiments, the sol will contain about 70% to about 90% byweight silicon alkoxide (e.g., TEOS), about 5% to about 25% by weightalcohol solvent (e.g., anhydrous ethanol), an acid catalyst (e.g., lessthan about 0.1% by weight when using HCl) and the balance water.

In some embodiments, the sol contains 70% to 90% tetraethylorthosilicate (TEOS) by weight, 8% to 25% ethanol by weight, 1% to 10%water by weight, and an acid catalyst. In some embodiments, the solcontains 75% to 85% by weight TEOS, 12% to 20% by weight ethanol, andabout 2% to 5% by weight water. An exemplary sol contains about 80% byweight TEOS, about 17% by weight ethanol, and about 3% by weight water.In some embodiments, the acid catalyst is HCl. For example, the sol maycontain less than about 0.1% HCl by weight. For example, the sol maycontain from 0.02% to 0.08% HCl by weight. In various embodiments, thesol does not contain an organic polymer, or other substantial reagents,such that the fiber composition will be substantially pure SiO₂. Invarious embodiments, the sol does not include inorganic salts (e.g.,sodium chloride, lithium chloride, potassium chloride, magnesiumchloride, calcium chloride, and/or barium chloride), nor are, in variousembodiments, inorganic salts mixed with other components of the sol orinto the sol itself. In various embodiments, the fiber composition doesnot include metals or metal oxides (e.g., TiO₂ or ZrO₂). In variousembodiments, the fiber composition consists essentially of SiO₂, i.e.,contains only SiO₂ and unintentional impurities, and, in someembodiments, species and/or complexes resulting from the incompleteconversion of the sol to SiO₂ (e.g., water and/or chemical groups suchas ethoxy groups, silanol groups, hydroxyl groups, etc.).

According to various embodiments, the first mixture and the secondmixture are combined by dripping or titrating the second mixture intothe first mixture, preferably with agitation. The combined mixture isthen further processed by allowing the sol to ripen in a controlledenvironment until a substantial portion of the alcohol solvent hasevaporated to create a sol-gel suitable for electrospinning.

In various embodiments, the sol is not exposed to heat over 150° F. orheat over 100° F., so as to avoid accelerating the transition.

In exemplary embodiments of the invention, the controlled environmentmay include an enclosure with at least one vent and optionally anexhaust fan to draw gases away from the mixture. The enclosure mayinvolve controlled conditions in terms of humidity, temperature, andoptionally barometric pressure. For example, the humidity may becontrolled (e.g., via use of conventional humidifiers and/ordehumidifiers) within the range of about 30% to about 90%, such as fromabout 40% to about 80%, or in some embodiments, from about 50% to about80%, or from about 50% to about 70% (e.g., about 55%, or about 60%, orabout 65%). Some humidity can be helpful to slow evaporation of solvent,and thereby lengthen the window for successful electrospinning. In someembodiments, the temperature is in the range of from about 50° F. toabout 90° F., such as from about 60° F. to about 80° F., or from about65° F. to about 75° F. In some embodiments, barometric pressure isoptionally controlled (e.g., using a low pressure vacuum source such asa pump or a fan). By controlling the environmental conditions duringripening, the gel can be electrospun during the time when spinning isoptimal, which can occur in a small window of only several minutes ifthe ripening process is too accelerated, such as with direct heat. Whenripening the sol at a constant humidity of about 55% and temperature ofabout 72° F., the sol will ripen (gelatinize) in a few days, and thewindow for successful electrospinning can be expanded to at leastseveral hours, and in some embodiments several days. In variousembodiments, the ripening process takes at least 2 days, or at least 3days in some embodiments. However, in various embodiments the ripeningdoes not take more than 10 days, or more than 7 days. In someembodiments, the ripening process takes from 2 to 7 days or from 2 to 5days or from 2 to 4 days (e.g., about 2, about 3, or about 4 days). Invarious embodiments, the sol-gel is spinnable well before it transitionsinto a more solidified, non-flowable mass.

The enclosure space for ripening the sol-gel may include a vent on atleast one surface for exhausting gases from within the enclosure, andoptionally the vent may include a fan for exhausting gases producedduring the ripening process. The enclosure space may optionally includea heating source for providing a nominal amount of heat within theenclosure space, to maintain a preferred temperature. In someembodiments, a source of humidity (e.g., an open container of water orother aqueous, water-based liquid) is provided within the enclosureenvironment to adjust the humidity to a desired range or value. Theenclosure may further include one or more environmental monitors, suchas a temperature reading device (e.g., a thermometer, thermocouple, orother temperature sensor) and/or a humidity reading device (e.g., ahygrometer or other humidity sensor).

In some embodiments, the sol-gel is electrospun after a ripening processof at least 2 days, or at least 36 hours, or at least 3 days, or atleast 4 days, or at least 5 days at the controlled environmentalconditions (but in various embodiments, not more than 10 days or notmore than 7 days under the controlled environmental conditions). Byslowing the ripening process, the ideal time to spin the fibers can beidentified. The weight of the sol-gel can be used as an indicator ofwhen the sol-gel is at or near the ideal time to electrospin. Withoutintending to be bound by theory, it is believed that the viscosity ofthe sol-gel is a poor determinant for identifying the optimal time forelectrospinning. For example, in various embodiments, the sol-gel isfrom about 10% to about 60% of the original weight of the sol (based onloss of alcohol solvent during transitioning). In some embodiments, thesol-gel is from 15 to 50% of the original weight of the sol, or in therange of about 20 to about 40% of the original weight of the sol.

In some embodiments, the sol-gel is ripened for at least 2 days, or atleast 36 hours, or at least 3 days, or at least 4 days, or at least 5days, and is electrospun when the ethylene vapors produced by thecomposition are between about 10% and about 40% of the vapors producedby the starting sol, such as in the range of about 10% and about 25%,such as in the range of about 10 to about 20%. Ethylene is a colorlessflammable gas with a faint sweet and musky odor (which is clearlyevident as solvent evaporation slows). Ethylene is produced by thereaction of ethanol and acid. Ethylene can optionally be monitored inthe vapors using a conventional ethylene monitor. In other embodiments,gases produced by the sol during the sol ripening process are monitoredto determine the suitable or optimal time for electrospinning. Gasprofiles can be monitored using gas chromatography.

The processing of the sol-gel mixture may require stirring or otheragitation of the mixtures at various intervals or continuously due tothe development of silicone dioxide crystalline material on the topsurface of the mixtures. This development of crystalline material on thetop surface slows the processing time and it is believed that thecrystalline material seals off exposure of the mixture to the gaseousvacuum provided within the enclosure space. In some embodiments, anysolid crystalline material is removed from the mixture.

Upon completion of the sol-gel process, the sol-gel is then electrospunusing any known technique. The sol or sol-gel may be preserved (e.g.,frozen or refrigerated) if needed (and such time generally will notapply to the time for ripening). An exemplary process forelectrospinning the sol-gel is described in Choi, Sung-Seen, et al.,Silica nanofibers from electrospinning/sol-gel process, Journal ofMaterials Science Letters 22, 2003, 891-893, which is herebyincorporated by reference in its entirety. Exemplary processes forelectrospinning are further disclosed in U.S. Pat. No. 8,088,965, whichis hereby incorporated by reference in its entirety.

In an exemplary electrospinning technique, the sol-gel is placed intoone or more syringe pumps that are fluidly coupled to one or morespinnerets. The spinnerets are connected to a high-voltage (e.g., 5 kVto 50 kV) source and are external to and face toward a groundedcollector drum. The drum rotates during spinning, typically along anaxis of rotation approximately perpendicular to the spinning directionextending from the spinnerets to the drum. As the sol-gel is supplied tothe spinnerets from the syringe pumps (or other holding tank), the highvoltage between the spinnerets and the drum forms charged liquid jetsthat are deposited on the drum as small entangled fibers. As the drumrotates and electrospinning continues, a fibrous mat of silica fibers isformed around the circumference of the drum. In various embodiments, thespinnerets and syringe pump(s) may be disposed on a movable platformthat is movable parallel to the length of the drum. In this manner, thelength along the drum of the resulting fiber mat may be increasedwithout increasing the number of spinnerets. The diameter of the drummay also be increased to increase the areal size of the electrospun mat.The thickness of the mat may be largely dependent upon the amount ofsol-gel used for spinning and thus the amount of electrospinning time.For example, the mat may have a thickness of greater than about ⅛ inch,or greater than about ¼ inch, or greater than about ⅓ inch, or greaterthan about ½ inch.

Silica fiber mats and compositions produced in accordance withembodiments of the present invention exhibit one or more beneficialproperties when compared to fiber compositions spun at non-optimal times(e.g., with inadequate ripening of the sol-gel). For example, fiber matsand compositions in accordance with embodiments of the invention do notburn, char, or visibly degrade upon direct application of heat or openflame. In contrast, various fiber compositions spun at non-optimal timeswill exhibit charring and/or visible color change when exposed tosufficient heat or open flame. Moreover, fiber mats and compositions inaccordance with embodiments of the invention effectively wick moisture(e.g., water or bodily fluids), absorbing such fluid into the fiber mat.In contrast, various fiber compositions spun at non-optimal times willnot visibly absorb or wick moisture even when directly applied thereto;such compositions tend to be hydrophobic. Finally, fiber mats andcompositions in accordance with embodiments of the invention are fluffyand may be easily shaped to uneven, non-uniform, and/or non-planar(e.g., curved) surfaces or shapes without fracturing or loss ofstructural integrity; thus, such compositions may be readily applied toor conformed to a variety of different surfaces. In contrast, variousfiber compositions spun at non-optimal times tend to be flat,plate-like, brittle, and will at least partially fracture if excessivelymechanically shaped or bent.

Fiber layers can be easily separated from the mat for, e.g., applicationto wounds or to damaged or inflamed tissue. In some embodiments, thecomposition is electrospun with a thickness of from about ⅛ inch toabout ½ inch. For example, the composition may be electrospun with athickness of greater than about ⅛ inch, or greater than about ¼ inchthick, or about ¼ thick in some embodiments.

In some embodiments, the fiber composition is applied to the tissue orwound as a thin layer of fibers, e.g., just enough to cover the woundsurface. Often, the wound will quickly absorb the fibers. The process isrepeated once fibers are no longer visible on the wound. For example, insome embodiments, fibers are reapplied 2 to 5 times per day. In someembodiments, the fiber composition is processed into a fine powder ordust, and the powder or dust is applied to the tissue. For example, asheet of silica fibers can be rubbed through one or more screens, and arange of powder sizes obtainable by varying mesh size. In someembodiments, the powder or dust is mixed with a topical composition,such as a lotion, ointment, paste, cream, foam, or gel. In theseembodiments, the topical composition may comprise one or morepharmaceutical or antimicrobial agents, such as an antibiotic, anantiseptic, an anti-inflammatory agent, or immunosuppressant.

In various embodiments, after completion of the electrospinning processand removal of the mat from the drum, the mat (or a portion thereof) maythen be divided into small fibrous fragments that may be incorporatedinto a topical composition or other composition. The resulting fibrousfragments are each intertwined collections of silica fibers, rather thanunitary solid particles. In some embodiments, the electrospun mat may befractured, cut, ground, milled, or otherwise divided into smallfragments that maintain a fibrous structure. In some embodiments, themat (or one or more portions thereof) is rubbed through one or morescreens or sieves, and the mesh size of the screen determines, at leastin part, the size of the resulting fibrous fragments produced from theelectrospun mat. For example, the mat or mat portions may be rubbedthrough a succession of two or more screens having decreasing mesh sizes(e.g., screens having mesh numbers of 100, 200, 300, or even 400), inorder to produce a collection of fibrous fragments having the desiredsizes.

As used herein, the term “fibrous fragments” (or “fibrous-matfragments,” or simply “fragments”) refers to small dust-like particles,parts, or flakes of a fibrous mat having an average dimension larger(e.g., 5×, 10×, or even 100×) than the width of at least some of thefibers of the mat. In various embodiments, the average size of a fibrousfragment is in the range of approximately 20 μm to approximately 200 μmalong the longest axis. Fibrous fragments may thus resemblemicroscopic-scale versions of the electrospun mat itself, e.g.,intertwined collections of silica fibers, and thus typically are porous.Thus, fibrous fragments may be contrasted with other types ofmicro-scale particles, such as the substantially spherical particlesused in colloidal silica, which are each unitary, individual units orgrains, rather than small collections of fibers.

Application of the composition during the healing process can providefor accelerated healing, of both acute and chronic wounds, and canprevent or reduce tissue scarring. When the topical composition isapplied to the skin that has a blemish like acne, cracks in skin, smallscrapes etc., the scaffolding is left behind in the small wound forcells to grow into. This speeds up the healing process and helps toreduce scarring. In some embodiments, the composition in lotion form isapplied to the cracked skin (e.g., on the face or hands) to improvetolerance of the skin to the environment, such as sun, wind, and cold,thereby reducing the impact of age and environment on the appearanceand/or function of the skin.

In some embodiments, the subject is a mammal. Subjects includeveterinary patients such as a dog, cat, or horse, among others. In someembodiments, the patient is a human patient. The tissue can be of anyorgan, but in some embodiments comprises skin, muscle, or bone. In someembodiments, the composition is applied to a skin lesion, ulcer, wound,burn, cut, scrape, or blister.

In some embodiments, particularly for chronic or difficult to healwounds, the fiber scaffold normalizes the wound environment, includingtemperature dysregulation, may reduce pain and inflammation at the woundsite, and/or provides a scaffold for dermal cells to multiply and growinto (e.g., without full, natural deposition of collagen).

In some embodiments, the wound is a burn, scrape, or cut, or a minorwound that does not go deeper than the base lamina. In such embodiments,treatment with the fiber scaffold for 1 to 7 days, e.g., from 3 to 5days (about 4 days) is sufficient for substantially complete healing. Insuch embodiments, fibers are applied once to four times daily to coverthe wound. Fibers are generally reapplied when fibers are no longervisible in the wound.

In some embodiments, the wound includes damage including or past thebase lamina. Such wounds may require treatment for several weeks (e.g.,from 2 to 8 weeks), or in some embodiments, several months (e.g., from 1to 4 months) for very severe wounds. In some embodiments, the wound is adiabetic ulcer, chronic pressure sore, gangrenous wound, or amputationwound. For difficult or hard to treat wounds, such as gangrenous woundsor wounds with substantial necrotic tissue (e.g., necrotizingfasciitis), the fiber compositions may mimic the healing process, andinduce gene expression and/or environment conducive to healing. Further,application of the fibers will bypass the need for deposition of naturalcollagen during the uncontrolled inflammatory state. Further, bacteriaat the wound site cannot easily penetrate the fiber to get to the wound.In these embodiments, fibers are applied once to four times daily tocover the wound. Fibers are generally reapplied when fibers are nolonger visible in the wound. A wound cover can by employed wherenecessary, as long as air and oxygen is not restricted from the wound.

In some embodiments, because the fiber material substantially reducespain from the wound site, the patient may be able to forgo therapy witha pain medication such as an opioid.

In some embodiments, the fibers may be applied to a rash or othermanifestation of skin inflammation (e.g., shingles, or an autoimmunerash or lesion, or allergic rash), resulting in reduction in pain and/orinflammation. In some embodiments, the fibers are applied with a gel orcream or other topical composition to mediate adherence of fibers tosubstantially intact skin.

In some embodiments, the subject has a genetic blistering disease, suchas epidermolysis bullosa (EB), which is a group of mainly inheritedconnective tissue diseases that cause blisters in the skin and mucosalmembranes. It is a result of a defect in anchoring between the epidermisand dermis, resulting in friction and skin fragility. EB often involvesformation of blisters following trivial trauma.

In some embodiments, the subject has EB simplex, which results inblisters at the site of rubbing, and typically affects the hands andfeet. In some embodiments, the subject has Junctional epidermolysisbullosa, which affects laminin and collagen. Junctional epidermolysisbullosa also presents with blisters at the site of friction, especiallyon the hands and feet. Dystrophic epidermolysis bullosa is an inheritedvariant affecting the skin and other organs, and involves skin that isvery fragile. Dystrophic EB is caused by genetic defects (or mutations)within the gene encoding the protein type VII collagen (collagen VII).

The human skin consists of two layers: an outermost layer called theepidermis and a layer underneath called the dermis. In individuals withhealthy skin, there are protein anchors between these two layers thatprevent them from moving independently from one another (shearing). Inpeople born with EB, the two skin layers lack the protein anchors thathold them together, resulting in extremely fragile skin. Even minormechanical friction (like rubbing or pressure) or trauma will separatethe layers of the skin and form blisters and painful sores. Sufferers ofEB have compared the sores with third-degree burns.

In some embodiments, when the fiber composition is applied to EBblisters, sores, wounds, or lesions, the composition will becomeintegrated with the healing tissue including the base lamina in someembodiments, and help anchor the skin. Thus, over time, the skinexhibits improved integrity as sores and blisters are treated. Further,the reduction in pain can be important for these patients to performdaily activities, such as bathing or traveling.

The thickness of fiber that is applied to the wound depends on the depthof the wound, but generally just enough fibers are applied to cover thewound. The composition may be reapplied after fibers are no longervisible at the wound site. The composition may also be freshly reappliedafter bathing. It is believed, without wishing to be bound by theory,that the fibers become integrated with the regenerated tissue at thewound site.

While the wound in some embodiments is not covered with any other wounddressing, in some embodiments other wound dressings can be employed. Forexample, in some embodiments the wound is not covered (other than thefiber composition), allowing exposure of air and therefore sufficientavailability of oxygen. However, for more severe wounds a dressing maybe needed. Preferably, the dressing is a light covering that will notlimit oxygen to the site. Generally, the fibers will not be removed.Since they are not biodegradable, they will become part of the newtissue. For shallow wounds, the scaffold is likely shed along with theskin tissue that integrates with it.

In some embodiments, the wound is a skin cancer lesion, such as amelanoma or squamous cell carcinoma (SCC) or basal cell carcinoma (BCC)lesion or ulcer. By application of the fibers to the lesion, theoutgrowth of malignant cells (including cancer stem cells) is preventedor reduced, while normal cells are able to grow in the fiber network.Without wishing to be bound by theory, it is believed that the cancercell phenotype is less able to populate the fiber matrix than normalcells. Further, cancers may rely on their ability to degrade collagen togrow, such that cancer cells are restricted from growing by theirinability to degrade the fiber scaffold.

In other applications, fiber compositions in accordance with embodimentsof the present invention may be added to various other compositions toimprove one or more mechanical and/or thermal properties thereof, asdetailed in U.S. Provisional Patent No. 62/643,946 filed Mar. 16, 2018,the entire disclosure of which is incorporated by reference herein.Specifically, entire silica fiber mats, or sections thereof may beutilized. In other embodiments, a silica fiber mat or portion thereofmay be broken into a plurality of fragments (e.g., fibrous fragments),or even into a powder, for use as a beneficial additive with a(typically liquid or gelatinous) composition in order to impartadvantageous thermal and/or mechanical properties thereto. For example,the fiber composition may be incorporated within paints or othercoatings (e.g., adhesives, epoxies, etc.) in order to increase thethermal resistance per unit area (i.e., the “R-value”) of thecomposition once it is applied. In other embodiments, the fibercomposition (e.g., in the form of a mat, mat portion, fibrous fragments,and/or powder) is added to structural compositions, such as epoxies orurethanes, in order to increase the mechanical strength and/or impactresistance of the material once it is formed (e.g., molded) into a solidobject. The fiber composition may also be mixed into a liquid, which maysubsequently be applied to articles such as fabrics to impart beneficialcharacteristics thereto. The liquid composition in such embodiments maydry onto the article and become a portion thereof or a layer thereon.For example, silica fiber-containing compositions may be applied toclothing to impart fire resistance or impact resistance thereto in themanner of a fire-resistant suit or an armored or bullet-proof vest.

Embodiments of the invention will now be described with respect to thefollowing examples.

EXAMPLES Example 1 Preparation of Silica Fiber Composition

SiO₂ fibers were prepared using an electrical spinning process, where asol-gel is spun onto a roller system creating a sheet. The sol-gel ismade in two parts. First, TEOS is mixed with ethanol, and then a secondmixture containing HCl, water, and ethanol is titrated into the mixture.The sol-gel is then allowed to ripen for a few days under controlledconditions before spinning.

In one example, the first sol was made by weighing out 384 grams of(TEOS) tetraethyl orthosilicate 98% and 41.8 grams of anhydrousdenatured ethanol, and pouring together. The first sol was allowed tolet stand in a beaker and a magnetic stirrer was used to create ahomogenous solution. The second sol was made by weighing 41.8 grams ofanhydrous denatured ethanol, 16.4 grams of distilled water, and 0.34grams of hydrochloric acid, which was then poured together and mixed for8 seconds with a magnetic stirrer until a homogenous second sol wasformed.

The second sol was then poured into the titration device, which wasplaced above a beaker containing the first sol . The titration devicethen dripped about 5 drops per second until a third sol was formedmixing the first sol and the second sol. During the dripping process,the first sol continues to be mixed with a magnetic stirrer while thesecond sol is dripped into the first sol.

The combined third sol was then placed into an enclosure box. A lowpressure vacuum is provided by a fan on medium speed to remove fumes. Inthe experiment, the air temperature within the box was 72° F. with 60%humidity. In the experiment, the third sol was allowed to sit andprocess for about three (3) days. By ripening the sol-gel slowly overseveral days, the sol-gel will transition slowly such that the idealtime to electrospin can be identified.

The mixtures were agitated daily to reduce the build-up of crystallinestructures. The third sol begins to transition to sol-gel withevaporation of the alcohol solvent. Sol-gel may be monitored todetermine an approximate amount of C₂H₄ (ethylene) in the vapors, whichcan be in the range of about 10-20% relative to the original sol beforeripening. Upon proper gelatinization, the sol-gel is loaded into theelectrospinning machine or is frozen to preserve for electrospinning.Proper gelatinization occurs when the total mass of the sol-gel wasbetween about 100 grams and about 180 grams.

The above example can be scaled appropriately to produce desirablestructures. To further identify the ideal time to electropsin, portionsof the gel can be dripped into the electric field to evaluate theproperties of the resulting fibers.

FIGS. 1A-1D are scanning electron microscopy (SEM) images of fibers spunin accordance with this disclosure (50, 100, 200, and 500 micron scalesshown). As shown, the fibers are flexible, smooth, dense, and continuous(not fractured). Material with these properties is ideal for treatingwounds and animal tissues (e.g., as a collagen mimetic).

FIGS. 2A-2D are SEM images of fibers that were electrospun at anon-optimal time (before the sol-gel was fully ripened) (50, 100, 200,and 500 micron scale shown). The fibers appear rigid, with manyfractures visible, and with formation of clumps. FIG. 3 shows an SEMimage (20 micron scale is shown) of fibers from a similar material,where the fibers are clearly rigid with many fractures clearly evident.

FIG. 4 shows a fiber mat spun in accordance with the disclosure. Theflexibility and continuity of the fibers allows mats to be spun at athickness of ¼ inch or more. The mat has a soft, flexible texture, andallows for layers of fibers to be easily separated for covering a woundbed. FIGS. 5A and 5B compare a silica fiber mat that was electrospunwhen the sol-gel was ripened in accordance with this disclosure (FIG.5A) to a fiber mat that was spun too early, before the sol-gel wasoptimally ripened (FIG. 5B). The material in FIG. 5A has a soft texture,is very flexible, and can be spun at a thickness that is easily handledfor application of fiber layers to a wound. The material in FIG. 5B isbrittle, inflexible, thin, and layers of fiber cannot be easilyseparated for covering the surface area of a wound.

Example 2 Treatment of Burns

Fibers were applied to first and second degree burns to the face of anadult male. The amount applied was just enough to cover the wound sites,with the thickness of the fibers based on the depth of the wound. Afterinitial application of the fibers, additional fibers were added oncefibers were no longer visible. After 4 days burns were barely visible.

Fibers were applied to second degree burns to the arm of an adult male.Application of thin sections of material to the burn wound is shown inFIG. 6.

Fibers were applied to2nd degree burns on the feet of an adult woman,with substantial healing shown in a four-day period. After initialapplication of the fibers, additional fibers were added once fibers wereno longer visible. Fibers were also reapplied after bathing. A pictureof the burns pretreatment and pictures taken in 4-day intervals (duringtreatment) are shown in FIGS. 7A, 7B, 7C, and 7D.

Example 3 Treatment of Amputation Wound

The fiber scaffolding was applied to a gangrenous wound site where thetoe had been amputated. The wound was a diabetic wound, which areextremely hard to heal, and difficult to stop the necrotic processes.

The wound healed in about 5 to 6 weeks with application of the fibermatrix. Prior to treatment, the foot was at risk of needing amputation.However, after treatment with the fibers, the foot was ultimately saved.

Example 4 Treatment of Animal Wounds

The fiber scaffolding was applied to a deep wound on a dog's leg, whichwas recommended for amputation. After treatment for 2-3 weeks, the woundwas fully healed, and a full covering of fur developed over the woundwithin 3 months. Pictures of the wound with fiber graft are shown (FIG.8A), and again after about 3 months of treatment (FIG. 8B).

The fiber scaffolding was applied to a deep wound on a horse's leg,which was ripped open by a fence. The wound was causing the horse tolimp badly. Wounds on horses are very hard to heal, especially wounds ontheir legs. The fibers were applied at night while the horse was in thebarn (FIG. 9A). The next morning the horse was trotting limp-free,suggesting that the horse no longer had the same pain sensations fromthe wound site. The same wound is shown after 4 days of treatment inFIG. 9B. That wound is now fully healed (FIG. 9C).

Example 5 Treatment of Pressure Sores

A paraplegic adult male with a severe bed sore on his lower back wastreated with the fibers. The wound was a chronic wound that existed forat least 17 months. When a paralyzed person has a wound, instead offeeling pain, they tend to sweat profusely. When the fibers were addedto the wound, the subject stopped sweating. After treatment for severalmonths the wound is nearly healed.

Example 6 Treatment of Epidermolysis Bullosa (EB) wounds

A child with Epidermolysis Bullosa (EB) was treated by applying thefibers to open sores and blisters. Application of the fibers allowed thechild to take a bath without pain, eliminating the need for pain drugsduring bath time. Application of the fibers to a severe open wound onthe child's hand is shown in FIG. 10A. The same hand after healing isshown in FIG. 10B. When a rub test (to induce a blister) is conducted onthe healed site with the fibers, the skin does not blister.

Example 7 Treatment of Burns

Fibers were applied to second degree burns to the arm of an adult male.FIGS. 11A and 11B show the fibers applied to the wound a few days aftercommencement of treatment. The pain due to the burn subsidedconsiderably within one day of the initial treatment. FIGS. 11C and 11Dshow the healed wound eight days after the burn occurred. Healthy skinis evident across the entire wound site. New hair growth from the skinis also evident, and no evidence of scarring or scar tissue is present.

The terms and expressions employed herein are used as terms andexpressions of description and not of limitation, and there is nointention, in the use of such terms and expressions, of excluding anyequivalents of the features shown and described or portions thereof. Inaddition, having described certain embodiments of the invention, it willbe apparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the invention. Accordingly, thedescribed embodiments are to be considered in all respects as onlyillustrative and not restrictive.

What is claimed is:
 1. A method for improving integrity of injuredtissue in a subject, the method comprising applying a silica fibercomposition to said tissue without removing the silica fiber compositionfrom said tissue during and after healing of said tissue.
 2. The methodof claim 1, wherein the silica fiber composition is a permanent scaffoldthat supports tissue healing, regeneration, and/or integrity.
 3. Themethod of claim 1, wherein the composition acts as a collagenreplacement, and/or cell scaffold for wound healing.
 4. The method ofclaim 1, wherein the composition is prepared by electrospinning asol-gel.
 5. The method of claim 4, wherein the sol-gel is prepared withtetraethyl orthosilicate (TEOS).
 6. The method of claim 4, wherein thesol-gel contains 70% to 90% TEOS by weight, 8% to 25% ethanol by weight,an acid catalyst, and the balance water.
 7. The method of claim 6,wherein the sol-gel is allowed to transition for at least 2 days underconditions where humidity is within the range of about 40% to about 80%,and the temperature is within the range of 50° F. to 90° F.
 8. Themethod of claim 4, wherein the sol-gel is electrospun when the weight isat from 20% to 40% of the starting weight before ripening.
 9. The methodof claim 4, wherein the sol-gel is electrospun when the production ofethylene vapor is 10% to 20% relative to the peak production of ethylenevapors during ripening.
 10. The method of claim 1, wherein fibers of thesilica fiber composition have a variable diameter of from about 50 nm toabout 5 μm.
 11. The method of claim 1, wherein the composition consistsessentially of SiO₂.
 12. The method of claim 1, wherein the fibercomposition is applied to the tissue as a thin layer.
 13. The method ofclaim 1, wherein the fiber composition is processed into a powder ordust, and the powder or dust is applied to the tissue.
 14. The method ofclaim 13, wherein the powder or dust is mixed or suspended in a topicalcomposition.
 15. The method of claim 14, wherein the topical compositionis a lotion, ointment, paste, cream, foam, or gel.
 16. The method ofclaim 15, wherein the topical composition further comprises one or morepharmaceutical or antimicrobial agents.
 17. (canceled)
 18. The method ofclaim 1, further comprising reapplying the silica fiber composition tothe injured tissue once the silica fiber composition is no longervisible on the injured tissue.
 19. The method of claim 1, wherein theinjured tissue is not covered with any other wound dressing. 20.-30.(canceled)
 31. The method of claim 16, wherein the topical compositioncomprises an antibiotic or antiseptic.
 32. The method of claim 16,wherein the topical composition comprises an anti-inflammatory agent orimmunosuppressant.
 33. The method of claim 1, wherein the compositionprevents or reduces scarring of the tissue.
 34. The method of claim 1,wherein the subject is a mammal.
 35. The method of claim 34, wherein thesubject is a human patient.
 36. The method of claim 34, wherein thesubject is a cat, dog, or horse.
 37. The method of claim 1, wherein thetissue comprises skin.
 38. The method of claim 1, wherein thecomposition is applied to a skin lesion, ulcer, wound, burn, cut,scrape, or blister.
 39. The method of claim 1, wherein the compositionis applied to a diabetic ulcer.
 40. The method of claim 1, wherein thesubject has a genetic blistering disease.
 41. The method of claim 40,wherein the subject has epidermolysis bullosa.
 42. The method of claim1, wherein the composition is applied to a pressure sore or pressureulcer.
 43. The method of claim 1, wherein the composition is applied toa gangrenous wound or an amputation wound.
 44. The method of claim 1,wherein the tissue has a wound comprising a skin burn, cut, or scrape,and the composition is applied in layers in an amount that is sufficientto cover the wound.
 45. The method of claim 44, further comprisingreapplying the silica fiber composition to the injured tissue once thesilica fiber composition is no longer visible on the injured tissue. 46.The method of claim 1, further comprising applying a wound dressing overthe composition.